The invention relates to an image forming apparatus, a process cartridge, and a transfer device unit.
Some image forming apparatus, such as laser printers, include a transfer roller that is fixed to a body casing of the image forming apparatus, and a process cartridge that includes an image holding body. The process cartridge can be attached to and detached from the image forming apparatus through an opening provided in the body casing of the image forming apparatus. The attachable/detachable feature of the process cartridge allows the process cartridge to be replaced with another (e.g., new) process cartridge. The process cartridge may be replaced when, for example, low quality images are being formed because the process cartridge is not functioning properly (e.g., the process cartridge is out of developing agent and/or the image holding body is damaged). In some cases, however, there may be a need to replace the transfer roller if, for example, the transfer roller is damaged and thus, low quality images are being formed.
Japanese Laid-Open Patent Publication No. 2001-100550 discloses an image forming apparatus that attachably/detachably accommodates each of a process cartridge and a transfer roller. The attachable/detachable process cartridge and the attachable/detachable transfer roller are independently attached to and removed from the image forming apparatus by way of an opening in a body casing of the image forming apparatus. The attachable/detachable process cartridge and the attachable/detachable transfer roller are respectively attached to and removed from a predetermined process cartridge position and a predetermined transfer roller position of the image forming apparatus.
In the structure disclosed in Japanese Laid-Open Patent Publication No. 2001-100550, however, the predetermined transfer roller position is a narrow space deep inside the image forming apparatus (e.g., far from the opening in the body casing of the image forming apparatus). Thus, it is difficult to attach and detach the transfer roller to and from the predetermined transfer roller position.